A personal wireless area network (WPAN) is a network used for communication among computing devices (for example, telephones and personal digital assistants) close to one person. The devices may or may not belong to the person in question. The reach of a WPAN may be a few meters. WPANs may be used for interpersonal communication among the personal devices themselves, or for connecting via an uplink to a higher level network and for example the Internet.
The IEEE 802.15.3 Task Group 3c (TG3c) was formed in March 2005. TG3c is developing a millimeter-wave (mmWawe) based alternative physical layer (PHY) for the existing 802.15.3 Wireless Personal Area Network (WPAN) Standard e.g., IEEE 802.15.3-2003. This mmWave WPAN may operate in a band including 57-64 GHz unlicensed band defined by FCC 47 CFR 15.255 and may be referred to as “60 GHz”. The millimeter-wave WPAN may allow very high data rate (over 2 Gigabit per second (Gbps)) applications such as high speed Internet access, streaming content download (e.g., video on demand, high-definition television (HDTV), home theater, etc.), real time streaming and wireless data bus for cable replacement.
However, an mm Wave communication link is significantly less robust than those operating at lower frequencies (e.g. 2.4 GHz and 5 GHz bands) due to Friis transmission equation, oxygen absorption and high attenuation through obstructions. In addition, the mm Wave communication link may use a directional antenna and/or antennas array to increase the communication range. The use of a directional antenna makes a link very sensitive to mobility. For example, a slight change in the orientation of the device or the movement of a nearby object and/or person may disrupt the link.60 GHz communication standards tend to have both orthogonal frequency-division multiplexing (OFDM) and single carrier (SC) physical layers. In some standards only one of the physical layers is mandatory, and in some other standards neither of OFDM and SC is mandatory. In a Carrier Sense Multiple Access (CSMA) communication scheme a device may determine the packet length according to information included in the packet header and may use this information in order to avoid collisions with other devices transmissions.
However, devices using SC may not be able to decode the packet length in a received OFDM packet and devices employing OFDM may not be able to decode the packet length and may try to transmit packets while other devices are transmitting, which may cause collisions.
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